Exhaust pops on decel when cold

Marico

Joined
Apr 15, 2025
Messages
14
Location
Poland
Bike
...
Hello,
What could cause a ST1300 to produce exhaust pops when decelerating, but only while the engine is not warmed up?
I found a unit in excellent, almost factory condition with very low mileage, and during the inspection, I noticed this backfiring/pops behavior. Considering my recent adventures with the noise in the transmission thread, I'm now nitpicking everything...
 
It's normal for some unburned fuel to collect in the exhaust, especially when it's cool and running rich.

I don't ride until the engine is warm enough for normal idle speed, carbs or fuel injection.
 
Could be several different things.
The 5 way T on the vacuum lines is clogged up and dirty (common on low mileage garage queens)
Could be a loose vacuum line
You could be trying to ride it, or rev it while it's still running on the choke (sic) FI circuit.
It could have an aftermarket K&N Filter in it, that is causing a lean condition (they fit very poorly on these bikes).
You could have chewed wires on your injectors (common on low mileage garage queens)
Fouled plugs
Loose plug caps
The pair screens could be filthy and gummed up.
Etc. etc. etc.
 
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